Preface This book is an account of a world-wide organisation, the League of Nations, which came into existence in January 1920 and held its last meeting in April 1946, and its efforts to preserve world peace in one of the most tempestuous periods in modern history. The League failed, and some of the reasons for this are--given here. Nevertheless, during the Second World War none of the countries ranged against the Axis Powers doubted that after the war the struggle must be taken up again, this time with the United Nations Organisation, the headquarters of which, appropriately, were to be in New York. Yet today, after forty years, in which peace has been precariously maintained, the United Nations is almost as ' much a lost cause as the League was in the late 1930s. Its non-political work for economic and social co-operation, for aiding the developing countries, for health and education, drug control, and so on, continue, as did that of the League until the bitter end. But, as instruments for the collective maintenance of peace, the world now relies upon methods which the League and the UN were intended to supersede. Is there something basically false in the idea that the nations can combine their efforts to smother threats to world peace from whatever quarter they come? Must we rest content with a system (if indeed it be a system) of collective defence and balance of power which failed to prevent war in 1914 and again in 1939, and which, if it failed again, could hardly ensure the survival of our civilisation? This book examines the reasons why collective security in the period between the two world wars failed, and tries to assess how far this was a failure in the formula for collective security devised at the Paris peace conference in 1919, or of the inclemencies of the epoch in which the League existed, or of its human instruments, the men and (more in the background of affairs in those days) women who sought to make the system work, and, in some cases, to defeat it. The book therefore attempts to be more than a historical record, though it uses primary historical sources, especially on the British side, Britain having been, at all times, the most important League member and the country to which responsibility for the League's experience chiefly attaches. It is the study of an experiment, the failure of which shook the world. The book cannot hope to do more than examine the more important of the League's activities since the League's story is that of the world, in a truer sense than is that of the United Nations. But its subject is the collective maintenance of peace, and the League's work is always regarded from that perspective. For all its helplessness in the late 1930s, the League of Nations, wrote one of its most fervent supporters, the physicist Madame Curie, 'has a grandeur that commands our support'.